1. Field of the Invention
The invention relates generally to a method and apparatus for excavating a basement or like below grade opening.
2. Related Art
At a construction site, a basement is typically constructed by excavating a portion of a parcel of land. Typically, the excavation must be continually monitored to determine how much more earth needs to be excavated. In a conventional process, an elevation survey is performed utilizing a transit and a target. Commonly, the transit is a laser transmitter used on the ground area surrounding the opening and the target is a laser receiver attached to a grade stick. The grade stick, and thus the laser receiver, is placed into the opening area and as the excavation proceeds, the elevation differential between the target and bottom of the excavation is determined. With this information, the necessary additional excavation can be performed to achieve the desired elevation for the floor of the opening.
The conventional crew typically includes a surveyor or transit man and a rod man. The rod man carries the grade stick to the points selected by the surveyor and holds the grade stick in a generally upright or vertical orientation so that the desired data related to elevation can be obtained as the hole is excavated. Excavation is performed and continues intermittently between excavations until the desired elevation is obtained. This measuring and excavating process is repeated until the excavation floor is at the desired elevation and level.
The conventional surveying techniques described above can be slow and tedious, since a rod man is needed to move the grade stick to various locations. In addition, the rod man can be subjected to difficulties, such as pests, weeds, brush, and ultimately dangerous situations that may result from depths at the excavation site presenting a risk of cave in. Additionally, the requirement for a rod man increases the possibility for miscommunication between the surveyor and the rod man and the need for two people to accomplish excavation adds inherent costs in the excavation process.